Field of the Invention
The present invention relates to a touch screen, a touch panel, a display, and an electronic apparatus.
Description of the Background Art
A touch panel is a device that detects a touch of a finger or the like and specifies coordinates of a position of the touch. A touch panel is attracting attention as one of excellent user interface means. Various types of touch panels such as resistive film touch panels and capacitive touch panels are commonly available now. A touch panel typically includes a touch screen with a built-in touch sensor and a detection device for specifying coordinates of a position of a touch based on a signal from the touch screen.
A projected capacitive touch panel is an example of the capacitive touch panel (for example, see Japanese Patent Application Laid-Open No. 2012-103761). The projected capacitive touch panel allows detection of a touch even if a front side of a touch screen with a built-in touch sensor is covered with a protective plate such as a glass plate having a thickness of approximately several millimeters. The touch panel of this type has excellent ruggedness since the protective plate can be disposed on the front side. Further, the touch panel can detect a touch even when a user touches it with gloves on. Moreover, the touch panel is long-lived because the touch panel has no movable part that is mechanically deformed.
The projected capacitive touch panel includes, as detection wiring for detecting capacitance, a first series of conductive elements formed on a thin dielectric film and a second series of conductive elements formed above the first series of conductive elements with an insulating film therebetween, for example. These series of conductive elements three-dimensionally intersect each other at a plurality of intersections without electrically contacting each other. A detection circuit detects capacitance formed between an indicator such as a finger and the first series of conductive elements and the second series of conductive elements as the detection wiring, to thereby specify coordinates of a position of a touch of the indicator. Such a detection method is commonly referred to as a self-capacitance detection method (for example, see Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 9-511086 (1997)).
For example, there is a detection method for detecting a change in electric field, namely, a change in mutual capacitance, between a plurality of row-direction wires extending in a row direction and a plurality of column-direction wires extending in a column direction to specify coordinates of a position of a touch. Such a detection method is commonly referred to as a mutual capacitance detection method (for example, see Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2003-526831).
Both configurations of the self-capacitance method and the mutual capacitance method described above typically include a method for specifying, when an indicator such as a finger touches a planar area (detection cells) partitioned into a lattice pattern by the row-direction wires and the column-direction wires, coordinates of a position of the touch based on a balance between a detection value in a sensor block and a detection value in a detection cell near the sensor block.
In recent times, a touch panel formed of a fine-wire electrode made of a low-resistive metal material has been increasing instead of a touch panel made of a transparent conductive film such as indium tin oxide (ITO), which has been used, for the purpose of increasing size and speed of the touch panel. A liquid crystal module in which the touch panel including the fine-wire electrode is installed needs to suppress moiré caused by interference between a fine-wire electrode pattern and a black matrix (BM) pattern formed on a color filter (CF) substrate. For this matter, a technology of suppressing moiré by, for example, forming the fine-wire electrode and the black matrix so as to overlap each other in plan view is disclosed (for example, see Japanese Patent Application Laid-Open No. 2009-259063).
When a touch screen is mounted on the inner side of a polarizing plate on a display surface side of a liquid crystal panel in the liquid crystal module including the touch panel installed therein, a fine-wire electrode formed on the glass substrate for the touch screen may sometimes change, to an unexpected direction, a polarization direction of polarized light passing through a polarizing plate on the back side of the liquid crystal panel from a backlight. This causes a portion to be illuminated regardless of whether black is displayed, thereby lowering a contrast ratio.
Forming sensor wiring only in a direction of a polarization axis or a direction perpendicular to the polarization axis and forming the sensor wiring and a black matrix so as to overlap each other in plan view, as disclosed in Japanese Patent Application Laid-Open No. 2009-259063, are effective to suppress the decrease in the contrast ratio. However, if the sensor wiring is displaced from the black matrix due to manufacturing variations, portions having regular intervals between the sensor wiring and the black matrix relatively increase in length. Thus, interference of light easily occurs, which easily causes moiré.